Conventional LiDAR systems are used to determine distances from objects using time-of-flight of light generated by a laser. LiDAR systems may be used in fixed locations or on moving objects to capture data about those objects and/or a surrounding area.
Some LiDAR systems may employ a Geiger mode detector (e.g., Avalanche Photo-Diodes (APD)), or an array of detectors for detecting light reflected off of an object spaced a distance therefrom. The term “Geiger mode” refers to an application of a bias voltage which exceeds the breakdown voltage of the APD. When the APD is over biased, the detector operates in a metastable state where a single photon may cause an avalanche current. The avalanche current can then be detected using simple digital circuitry. In the case of LiDAR, the detection of an avalanche stops a timing circuit which in turn is used to measure the time of flight of a transmitted laser pulse to the object. The distance to the object can then be determined given the speed of light.
Despite the advantages of Geiger mode detectors, they suffer from certain drawbacks. For example, the Geiger mode arrays may comprise continuously triggering detectors (“hot detectors”). While the data from the hot detectors can be discarded during post processing, the hot detectors require a lot of processing power to filter the signal from the noise in real-time. Thus, it is desirable to provide an improved three-dimensional imaging system which employs LiDAR with an improved signal-to-noise ratio. Further, it is desirable to provide a LiDAR system capable of performing noise data filtering in real-time.